What is Coastal Transportation? - Definition & Causes

Instructor: Adrianne Baron

Adrianne has a master's degree in cancer biology and has taught high school and college biology.

We are going to discuss what coastal transportation is and look at the various methods by which coastal transportation can occur. The type of materials moved by each method will also be discussed.

Coastal Transportation

How did you get to the last place that you went to on vacation? Maybe you and your family took a car, bus, ship, train, or plane. These are all considered to be modes of transportation since they move you from one place to another.

Just as you move around, so do various substances that are in the ocean and sea. You may have seen this before if you have visited a beach, especially if it was windy when you were there. Perhaps one of your sandals came off and went into the water while you were on the beach. You spent some time looking for it right by where you lost it, but it was nowhere to be found.

You finally gave up and walked along the edge of the water on your way back to your hotel. Then, out of the blue, you ended up seeing your sandal, but it was nowhere near where you lost it! It was moved away from where you lost it by the water in a process known as coastal transportation. This is the movement of material from one place to another in the water or along the coastline.


Well, you can thank the wind for what happened to your sandal. The wind is one of the biggest driving forces for coastal transportation. That is because the wind is responsible for making the waves in the sea and ocean. Waves constantly move sand, pebbles, and other things around in the water.

On the Coast

Think for a minute about how waves move. One thing you will notice is that they do not flow straight forward onto the beach. They come onto the beach at a diagonal angle instead. When waves move forward in this manner onto the beach, this is called swash. After the wave has gone as far onto the beach as it can go, then it begins to move back out to the ocean or sea in a straight line. This is known as backwash.

The number 1 represents the coastline, 5 shows swash, and 6 shows backwash. Together they show the zigzag transportation of longshore drift.
Diagram showing longshore drift

As swash and backwash happen, whatever is on the coast gets moved down the coastline in a zigzag-like pattern. The movement of materials down the coast through swash and backwash is known as longshore drift.

In the Water

Some materials remain in the water while they are being moved. Waves are still the driving force for this type of coastal transportation. The first way that waves cause coastal transportation in the water is through floating. Floating is when something stays on the surface of the water. This occurs more so with lightweight objects, such as paper and plastic. Floating objects go wherever the waves go. The objects come onto the beach and go back out to the ocean by riding the waves.

Some items that are a bit heavier, but still not very heavy, may actually get suspended in the water. This means that they are just hanging out within the water. They are not floating on top, but they have not sunk to the bottom of the ocean or sea either. Hanging in the water will make these objects flow to the coastline, and oftentimes, they are left there through what is known as deposition. This is when waves leave items on the shore that flow there through swash.

At some point in time, maybe you got some ocean water in your mouth while you were playing in it and quickly realized that it is salty. It is salty because some substances, such as salt and other minerals, become completely dissolved in the water. This makes ocean water a solution because the salt becomes a part of the water that cannot be separated out. Since the salt is part of the solution, the salt goes everywhere the water goes.

Under the Sea

The last place where coastal transportation may occur is under the water on the ocean or sea floor. Some materials such as rocks, pebbles, and sand are too heavy to float or remain suspended in water. They are moved along the sea or ocean floor instead.

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